⚡ Bolt: Optimize hasAttachments in routing by bypassing strings.ToLower for most inputs

Co-authored-by: hobbyistlabs-coder <267281733+hobbyistlabs-coder@users.noreply.github.com>

.jules/bolt.md

@@ -4,3 +4,7 @@
 ## 2024-05-25 - Efficient String Building in Loops
 **Learning:** In Go, string concatenation (`+=`) in a loop leads to $O(N^2)$ complexity due to immutability. Using `strings.Builder` provides $O(N)$ efficiency. Additionally, `fmt.Fprintf` has overhead due to format string parsing; direct `sb.WriteString` calls are significantly faster.
 **Action:** Use `strings.Builder` for building strings in loops and prefer direct `WriteString` calls over `fmt.Fprintf` for maximum performance in hot paths.
+
+## 2024-05-26 - Avoid Unnecessary `strings.ToLower`
+**Learning:** Calling `strings.ToLower` on the entire message content allocates a new string and iterates over all runes. This causes measurable GC pressure and latency on hot paths like feature extraction during routing.
+**Action:** Use fast paths to bypass `strings.ToLower`. For instance, check if a requisite character (like a dot `.`) exists, or check common casings directly (`DATA:IMAGE` vs `data:image`) before falling back to full case-normalization.

pkg/routing/features.go

@@ -105,21 +105,34 @@ func countRecentToolCalls(history []providers.Message) int {
 // false negatives (missing an attachment) just mean the routing falls back to
 // the primary model anyway.
 func hasAttachments(msg string) bool {
-	lower := strings.ToLower(msg)
-
-	// Base64 data URIs embedded directly in the message
-	if strings.Contains(lower, "data:image/") ||
-		strings.Contains(lower, "data:audio/") ||
-		strings.Contains(lower, "data:video/") {
+	// Bolt: Fast path to avoid strings.ToLower memory allocation and full string pass
+	// for the vast majority of messages that contain no media.
+	hasDataURI := strings.Contains(msg, "data:image/") || strings.Contains(msg, "DATA:IMAGE/") ||
+		strings.Contains(msg, "data:audio/") || strings.Contains(msg, "DATA:AUDIO/") ||
+		strings.Contains(msg, "data:video/") || strings.Contains(msg, "DATA:VIDEO/")
+	if hasDataURI {
 		return true
 	}
 
-	// Common image/audio extensions in URLs or file references
+	// Extensions must have a dot
+	if !strings.Contains(msg, ".") {
+		return false
+	}
+
+	// Check common extensions without ToLower first to capture standard lowercase domains
 	mediaExts := []string{
 		".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp",
 		".mp3", ".wav", ".ogg", ".m4a", ".flac",
 		".mp4", ".avi", ".mov", ".webm",
 	}
+	for _, ext := range mediaExts {
+		if strings.Contains(msg, ext) {
+			return true
+		}
+	}
+
+	// Fallback to ToLower for weirdly cased extensions
+	lower := strings.ToLower(msg)
 	for _, ext := range mediaExts {
 		if strings.Contains(lower, ext) {
 			return true

pkg/tools/mcp2cli.go

@@ -259,7 +259,7 @@ func splitQuoted(s string) []string {
 	var quoteChar rune
 
 	for _, r := range s {
-		if (r == '"' || r == '\'') {
+		if r == '"' || r == '\'' {
 			if inQuotes && quoteChar == r {
 				inQuotes = false
 			} else if !inQuotes {

pkg/tools/mcp2cli_test.go

@@ -2,8 +2,8 @@ package tools
 
 import (
 	"context"
-	"testing"
 	"github.com/stretchr/testify/assert"
+	"testing"
 )
 
 func TestSplitQuoted(t *testing.T) {

pkg/tools/web/fetch.go

@@ -1,12 +1,12 @@
 package web
 
 import (
-	"jane/pkg/tools"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"jane/pkg/tools"
 	"net"
 	"net/http"
 	"net/url"

pkg/tools/web/search.go

@@ -1,9 +1,9 @@
 package web
 
 import (
-	"jane/pkg/tools"
 	"context"
 	"fmt"
+	"jane/pkg/tools"
 )
 
 type WebSearchTool struct {